Hi hredii,
There are some great points here already. I'm trying to understand exactly what you mean so I will try to look at the topic by using the terms in a sentence, "Thus and such they did or did not do as a matter of [i]personal conviction[/i]" or " I have several [i]personal conviction[u]s[/u][/i] that the Holy Spirit has pressed upon me personally that I do not attempt to hold others to, they are for me specifically."
The difficulty is trying to answer the question from a biblical standpoint. The word 'conviction' carries a couple of different meanings as it is translated from a few different Greek words. I think [i]Plerophoria[/i] is the closest to what you are talking about and it means "assurance" or "full assurance."
And he that [u]doubteth[/u] is damned if he eat, because he eateth not of faith: for whatsoever is not of faith is sin. (Romans 14:23)
There were in the New Testament era those who were still wrestling with whether or not things that were condemned under the old Covenant were now permissable under the New Covenant; in this case various foods. The Jews had dietary laws, etc. that were fulfilled in Christ. Some had not fully reckoned with that and could not yet eat certain things with a [i]clear conscience[/i]. For them to eat something believing it was sin would be sin. Faith is [i]right[/i] response to revelation. Sin is [i]wrong[/i] response to revelation. If the person believes something to be the revealed will of God (in this case not to eat certain things) then they are condemned if they eat. This is why clear bible teaching is important.
Some things are called 'personal convictions' because they are beliefs held by a person for some reason or another. In our parts in the early 1900 it was said to be a sin to drink coffee. This was preached from pulpits. Was it a sin? If a person works hard enough on it they could make a case for it being a sin and thats what they did. But we could do that with a lot of things in life. As late as 1979 the boys were made to swim in pants and a shirt at the pool (and it was NOT co-ed) lest someone look upon their nakedness. It may seem funny, but I was swimming in a pool at a youth camp fully dressed as if that pleased the Lord. I could just have easily made a case for it tempting God to nearly drown some boys. Such as it is.
Some issues are truly 'personal convictions'. they are things you abstain from that you do because you are vulnerable to [i]temptation[/i] in a certain area, that others may not be vulnerable in. This is more of a "make not provision for the flesh to fulfill its lusts" type 'personal conviction.'
God Bless,
-Robert